Manufacture of hypochlorite solutions by electrolytic methods.



No. 892 983. PATE T D W. P. DIGBY. N E JULY 14, 190s RITE soLUTIoNs BY ELEC TROLYTIG METHODS.

MANUPACTURE 0F HYPocHLo 6 SHEETS-SHEET 1.

APPLICATION FILED SEI-118. 1906.

No. 892,983. PATENTED JULY 14, 1908. W. P. DIGBY.

MANUFAGTUR'EDP HYPOGHLORITE SOLUTIONS BY ELECTROLYTIG METHODS.l

APPLICATION FILED SBPT,18, 1906.

6 SHEETS-SHEET 2.

` a Maf;

No. 892,983. PA'l'BNTED JULY 14, 1908.

W. P. DIGBY.

MANUFAOTURE 0F HYPOOHLORITE SOLUTIONS BY BLEOTROLYTIO METHODS.

. APPLICATION FILED SBPT.18.1906.

6 SHEETS-SHEET 3.

' #VVE/WOR.' WWA/asses.-

No. 892,983. PATENTED JULY 14, 1908.

W. P. DIGBY. MANUFAGTURE 0F HYPOGHLORITB SOLUTIONS BY ELBGTROLYTIC METHODS.

APPLICATION FILED SEP .18.1906.

T 6 SHEETS-SHEET 4.

W/T/VESSES.

` No. 892,983. PATENTED JULY 14, 1908.

W. P. DIGBY.

MANUFAGTURE 0F HYPOCHLORITE SOLUTIONS BY ELECTROLYTIG METHODS.

APPLIOATIUN F ILED SEPT 18 1906 6 SHEETS-SHEET 5.

k l S PATENTED JULY 14, 1908.

W. P. DIGBY. V MANUFACTURE 0F HYPOCHLORITE SOLUTIONS BY BLECTROLYTIC METHODS.

APPLIOATION FILED SE .18.1906. PT 6 SHEETS-SHEET 64 Mns/8553:

` 'WILLIAM POLLARD DIGBY, OF LONDON, ENGLAND.

MANUFACTURE OF HYPOCHLORITE SOLUTINS BY ELECTROLYTIC METHODS.

j Specification of Letters Patent.

Patented July 14, 1908.

Application Bled September 18. 1906. Serial No. 335,140.

T o all whom it may concern:

Be it known that I, WILLIAM POLLARD DIGBY, 012.82 Victoria street, Westminster, in the county of London, England, consulting electrical engineer, have invented certain new and useful Improvements- Relating to the Manufacture of Hypochlorite Solutions by Electrolytic Methods, of which the following is a specification.

This invention relates to themanufacture of solutions of hypoclilorites of sodium, magnesium, or calcium by electrolytic methods from their res ective chlorids.

In other electrolytic processes for the manufacture of hyochlorite solutions, the substances liberate at the anode and cathode are allowed to recombine in the main body of the solution which is being submitted to electrolysis, with the result that a complete decomposition ofthe chlorid Within the electrolyte becomes' an impossibility, and it is rarely that more than one-fourth of the chlorin initially present in the form of chlorid becomes converted into available chlorin in the hypochlorite form.

Now according to the present invention I prevent the recombination of the products iberated at the anode and cathode from tak-A ing place in thelmain body of. the electrolyte and provide that this recombination shall take place in a. compartment or compartments whereone of the products is liberated in a nascent condition. By this means the waste of'unconverted chlorid is revented or reduced, and the delivery of a lquid of any speciied strength can be regulated by va ing the inflow of liquor into the cathode cell.

According to my invention I may em loy a separate orousl cell or suitable 4 artltion around bot the anode and catho e plates disposed in the main body of the electrolyte whlch should have its salme constituents replenished from time to time. A verysmall .space is left between' the surface of the elec trode and the inner side of its cell. vI feed into the cathode cells either pure water or water containing in solution an alkaline substance such for exam le as caustic-soda or carbonate of soda. rom the cathode cell this liquor, much enriched by the alkaline products liberated at the cathode may be passed through a suitable cooling arrange-f ment, and is led into the anode cell where it may pass along a zig-zag course over the surface of the anode and between the anode and i its cell.

. uct may be rendered unstable,especia `in whic the gases are collected.

Here it absorbs the chlorin gas liberated at the anode, the result being that the caustic alkali solution is decomposed therein to form a hypochlorite o1' oxychlorid of the alkali present, the resultant liquor being led 0H for use. Inasmuch as considerable quan# tities of heat are liberated during the process of electrolysis, whereby the resultant rodlly in hot climates, the anode or cathode,'or both, may be made hollow and compressed gases such as ammonia may be allowed to expand therein. I find however thatthe cooling of the liquor on its passage from the cathode cell ,to the anode cell'as above mentioned may be dispensed with.

In the accompanying drawings, Figures 1, 2 and 3 illustrate by Way of example a suitable form of ap aratus embodying the invention and inten ed for working on a low voltage parallel system.` Fig. 1 is an end elevation with the end of the tank removed. Fig. 2 is a similar view at ri ht angles to Fig. 1 and in con'unction wit the enlarged sectional deta` Fig. 3 serves to show the construction of the casin s or cells e e. Fig. 4 is a sectional plan il ustrating a `form of apparatus adopted for a series system of a higher voltage. Fig. 5 is a sectional plan of a modified form of apparatus. Fig. 6 is a similar view illustrating an apparatus having a cooling means. Fig. 7 is a vertical section showin a construction having a covered top Fig. 8 is a vertical section of an apparatus in which the cells are horizontally arranged.

a, is an iron tank coated inside with Aa prepai ration of bitumen.

b b are bars of wood or ebonite from which are suspended the cathodes c c, two of which are shown with a central anode d by Way of illustration. The cathodes c c may be of iron, copper or zinc. They have each a' porous casing or cell e secured to them by ebonite bolts and distance pieces as shown, these cells being closed at the bottom and sides. The wires f f carry the current from each cathode to the negative pole of theA dynamo. The central anode d is of fraphite and is fitted with similar cas-ings or cells e c to those fitted to the cathodes; the Wire g carries the current from the positive pole of the dynamo.

h is an .inlet pipe to admit fresh water or water containing caustic soda or carbonate the pipe by a Siphon or pump.

with the ch cathode on its right face.

T e preferred construction of the casings or cells e e is shown in Figs. 2 and 3. lt comprises an outer casing of ebonite c or the like with slots cut vertically therein as seen in Fig. 2, next to this is placed a sheet of asbestos or other porous material k and within this another ebonite sheet k2 with slots cut horizontally therein as shown indotted lines in Fig. 3, the whole being clamped together by the ebonite bolts k, in Fig. 1 and held at a small distance from the electrode by the distance pieces.

It will be understood that the main electrolyte, for example sodium chlorid solution is decomposed by the electric current acting through the slots and porous material of the electrodes, the sodium ions passing to the cathodes and the chlorin ions to the anode, the solution of caustic soda formed at the cathode passes by the connections i i to the anode com artments and combines therein llorin to form sodium hypochlorid solution which is led away by the 1pe j.

When ure water is fed into t e cathode cells, it will he understood that it almost immediately takes up s'odium ions which percolate through the cathode cell walls, so that its conductivity is greatly increased.v

Fig. 4 is a sectional plan illustratin a form of apparatus for a series 'system o higher voltage. c is the tank and l an inlet pipe for the saline solution to be electrolyzed, which Hows in a zig-zag manner aroundthe electrodes m m to the outlet pipe Z as shown by the arrows. In the tank a the right hand electrode fm is connected to the positive pole of the circuit and acts as an anode on its left face while the left hand electrode ml is connected to the negative pole and acts as a The intermediate electrodes act as anodes on their left hand sides and as cathodes on the right. Each of the anode and cathode faces'is fitted with a cell or casing e similar to those described in the foregoing example and the anode and cathode compartments of each electrode communicate by orifices n, while the adjacent compartments of successive electrodes are connected by short overflow pipes or connections o. The fresh water or soda solution is admitted to the extreme cathode chamber at p and a liquid containing caustic soda overflows through the connections o into the adjacent anode compartment, whence it flows through an orifice a into the adjacent cathode compartment and so on through the series of electrodes to the final overflow outlet p', becoming fed alternately with caustic soda in the cathode compartments and free chlorin in the anode compartments, and gaining in hypochlorite as each stage is passed.

In the apparatus illustrated the anodes and cathodes are shown solid but they may as explained be made hollow and connected to any known system for expanding ainmonia or other compressed gas in their hollow interior. Such an arrangement will be understood without further explanation. Moreover baffles or obstructions may be provided in the anode and cathode compartments to cause, the liquid to take a zig-zag course over the surface of the electrodes.

For series working I do not confine myself to the method of circulation shown for the products of electrolysis. As an alternative, each cathode compartment may have its separate fresh water inflow and caustic soda outflow into a common sump, whence the alkaline liquor may be pumped so as to flow from anode compartment to anode compartment, becomin enriched from sta e to stage; or the alkaline uor obtained in t e cathode cell or cells may e so distributed as tobe led separately into each anode cell or compartment, each of which would have'a separate outflow. Such an apparatus is illustrated in Fig. 5, in which Z 1s the inflow and Z the .outflow of the saline solution -to be electrolyzed. VThe electrodes m'm are arran ed in a similar manner to that in Fig. 4 so t iat the electrolyte flows around them in a zig-zag course to the outlet I', and diaphragms e are fitted to the electrodes as before.

p2 is a fresh water pipe with inlets p3 each leading to a cathode com artment which are on the right faces of t e respective electrodes. The liquid from the cathode compartments flows out by separate connections p4 and a pipe p" to the sump s whence the cathode liquor is pumped by the pump r through the pipe tinto the right hand anode compartment and traverses the anode compartment in succession by the overflow pipes o', finally outflowing throu h pipe o2.

For series working, all t e electrodes will preferably be of gra hite and would be arranged as shown in IFig. 4, or a number of tanks, each separately designed for parallel working might be joined in series.

When it is desired to cool the liquor on its passage from the cathode compartment to the anode compartment, this can be done'by leading it through a tubular or other cooler before allowing it to enter the anode compartment instead of leading it from cathode to anode compartment by overflow or other direct connections as illustrated. Such a construction is shown in Fig. 6. *The ,arrangement of the electrodes in this figure is similar to that in Fig. and the saline solution iiows round them in the same Way being admitted at l and flowing out at l.` Freshl water is'admitted to the end cathode compartment by 'the pipe p and overflows through the cathode com artment in succes.

sion by the pipes p and t ence passes by the ipe p8 to the sump's, whence the pump r orces the cathode l1 uor through the coollng coil 'v and pipe g to t e se arat'e anode compartments by branches g. The outflow 4of the hy'pochlorite solution from these compartments runs away by the branches g2 and pipe g3.

vn lace of carrying the liquor from the catho e cell or cells to the anode cell or cells Fig. 7 shows such a construction. The arrangement of the electrodes and diaphragms is similar to that shown in Fig. 1, but the connections are different. The main saline elec- Atrolyte is contained in or circulated through the tank.- The anode and cathode compart-` ments are not connected together but a bell lshaped cover w is fitted overthe anode. In.

this cover the chlorin gas is collected and is sucked away bythe lum a: which delivers it through the pipe a: to t e bottom of each cathode compartment. The outiiow of the hypochlorite liquor froml the cathode compartments is shown ,at j.

Alternatively in lace of the arrangement of vertical electro es shown and described, the principle of my invention Inight in the case of parallel working or of single tanks in series be a plied to a tank or tanks in which the electrodes are fitted horizontally. In the latter event a mercury cathode may be employed and the cathode cell or diaphragm dispensed with. In this case the sodium or corresponding metal liberated at the cathode combines with the mercury in the known way and is thus isolated, prevented or largely prevented from being taken up by the main electrolyte, the amalgam formed at the cathode being led into a separate chamber and washed with water inthe known manner; the resulting caustic soda or correspondin alkaline solution is\then pumped or supplie between the. anode or anodes and the porous cell or cells thereof. The anode or anodes may be suspended above the mercury cathode in the known way. Fig. 8 shows in vertical section an arrangement such as 'just referred to. In this case'the electrode mis disposed horizontally in the tanka. The saline solution to be electrolyzed is admitted at l and flows out at l. The anode is fitted with a diaphragm e. The cathode is formed by a layer of mercury m with which the tank is kept supplied; no diaphragm is required in this case,` as the mercury itself actsA as the isolater for the liberated sodium, which it at once takes up and thus keeps separate from the chlorin evolved at the anode. IFrom the tank a the mercury sodium'amalgam asses by the pi e l and is sprayed by the eat 2 into a tan 3 through which a circulation of lwater is maintained. The resulting caustic solution is pumped from the tank 3 and delivered by the pipe 4 to the anode compartment 4 where it takes u the chlorin evolved, the resulting hypoch orite solution iowing away at 5. The mercury regenerated in the tank 3 is pumped back to the tank a, by the pump 6l These various modifications of arran ement and detail will be readily applied lEby practical men from the description above given, it being understood that while the union of the anode and cathode products ma be effected in either the anode or in the cat ode compartment, the essential feature of this invention lies in the fact that the recombination of the products does not take place inthel main body of thel electrolyte, but in the the main body` of electrolyte` the decomposition products liberated at the anode and cathode and conveying'one of said roducts from the electrode at which it is iberated into a cell or compartment closely adjacent to an electrode of opposite sign and shielded from the main body of electrolyte by a porous partition, substantially as and for the purpose s eciiied.

2. In t e electrolytic production of hypochlorite solutions, shiel ing the electrodes from the main body of electrolyte by porous partitions disposed in proximity to their res ective electrodes and forming porous cel s therefor, feedin a separate aqueous liquid through a cat ode cell and thence conducting it out of contact with the main body of electrolyte through an anode cell so that said li uid passes through cells of opposite si n su stantially as and for the purposes escribed.

3. In the electrolytic roduction of hy ochlorite solutions, shiel ing an anode aus a cathode from the main body of electrolyte by porous partitions disposed in (proximity.

to their respective electrodes an forming porous cells therefor connected by aconduit, eeding a separate aqueous liquid through the cathode cell and thence conducting it by .forming porous cells therefor, the cathode 10 cellsbeing connected to the anode cellsby conduits, and circulating a separate aqueous li uid through the cathode cells and anode cells and their connecting conduits substantially as and forthe purposes described l5 5. In the electrolytic manufactureof hypochloritesolutions, Ashielding an anode from the'main bodyY of electrolyte by .a porous l' partition disposed in proximity to said anode and forming a porous cell therefor, electro- 20 lyzing the main electrolyte by the said anode and a mercury cathode, Washing the result- A ing amalgam to form an alkaline solution and feeding said solution into the said' anode cell out of contact with the main electrolyte. y 6. In the electrolytic production of hypochlorite solutions bringing a decomposition product into contact at an electrode of opposite `sign With the nascent decomposltion seaess product liberated at said electrode of o )posite sign, while shielding both products rom the main body of electrolyte.

7. In the electrolytic production of hypochlorite solutions, inclosing from the main bodyof electrolyte the decomposition products liberated at the electrodes, conducting one of said products, out of contact with the main body of electrolyte to an electrode at which the other product is liberated in the nascent condition substantially as described. 8. In the electrolytic -production of hypochlorite solutions, inclosing from the main body of electrolyte the decomposition products liberated at the electrodes, conducting vone ofsaid products, out of contact with the main body of electrolyte, to an electrode at Which the other product is liberated in the nascent condition and cooling the electrodes by expanding a compressed gas therein, substantially as described.

In Witness whereof, I have hereunto signed my name in the presence of two subscriliing witnesses.

WILLIAM POLLARD DIGBY. Witnesses:

HENRY SrMoNs BAKER, ALFRED BEEsLEY CAMPBELL. 

